MUTATIONS SOMATIC CELLS VS GAMETES

MUTATION = ALTERATION OF AN ORGANISM’S DNA Results from Results from A malfunction during meiosis A malfunction during meiosis Exposure to mutagens (anything that can cause a change in DNA) Exposure to mutagens (anything that can cause a change in DNA)

MALFUNCTION DURING MEIOSIS - NONDISJUNCTION

The cells in the video will become gametes The cells in the video will become gametes Two of the gametes are normal; one does not have enough chromosomes; one has too many chromosomes Two of the gametes are normal; one does not have enough chromosomes; one has too many chromosomes If the gamete with too many chromosomes becomes part of zygote (is fertilized or does the fertilization), the baby will have a disease called trisomy If the gamete with too many chromosomes becomes part of zygote (is fertilized or does the fertilization), the baby will have a disease called trisomy Ex. Trisomy 21 = Downs syndrome Ex. Trisomy 21 = Downs syndrome Look in your notebook for other examples Look in your notebook for other examples

MALFUNCTION DURING MEIOSIS - NONDISJUNCTION This is a karyotype – it is used to identify chromosomal mutations. This person has Downs syndrome aka Trisomy 21

MALFUNCTION DURING MEIOSIS - NONDISJUNCTION This karyotype reveals Klinefelter’s syndrome

MALFUNCTION DURING MEIOSIS - NONDISJUNCTION Because these kinds of mistakes happen during gamete formation, they are passed to offspring. Because these kinds of mistakes happen during gamete formation, they are passed to offspring. But what about somatic cell mutations? But what about somatic cell mutations?

SOMATIC CELL MUTATIONS Somatic cell (body cell) mutations contribute to the aging process and cancer. Somatic cell (body cell) mutations contribute to the aging process and cancer. They ARE NOT passed to offspring They ARE NOT passed to offspring They are caused by being exposed to a mutagen AFTER a person is born. They are caused by being exposed to a mutagen AFTER a person is born. Ex. A person smokes heavily and develops lung cancer. This person later becomes father or mother to a baby. The baby DOES NOT inherit it’s parent’s lung cancer. Ex. A person smokes heavily and develops lung cancer. This person later becomes father or mother to a baby. The baby DOES NOT inherit it’s parent’s lung cancer. Exceptions: Some cancers can be inherited. Exceptions: Some cancers can be inherited. One type of breast cancer can be passed from mother to child. It is NOT the result of exposure to a mutagen after a person is born. One type of breast cancer can be passed from mother to child. It is NOT the result of exposure to a mutagen after a person is born.